MII: ORGANS OF mi: MIIMH.I: GERM i i 





of tin* fundament of tin- IIM-, >i,ephro> at tin- -aim- time. The>e ha\e 

 to d<> with the evolution of the Miillerian duct and the seximl Ofg 



(-/) '/'//. K&Uerian Duct. 



Tin- Mullerian duct is a canal which i> found lying at lir>t | arallel 

 and close to the me>onephric duct in the eml.rvov <>f imt Vertebrates 



(Selachians, Amphi I'ii. Keptiles. Uinls, Mammals). It i- a canal tliat 



i> established in l.oth sexes in tin- saim- 

 manner, hut subsequently aojuiivs in each 

 a dillerent t'unction. It takes its origin 

 in the lower Vertel.rates J'roin the meson.- 

 phric duct, as can be most easily followed 

 in the Selachians (SKMi'ER, BALFOUR, 

 1 1 n i i M A x N). In this case the mesonephric 

 duct hic-oiiu-s enlarnred. acquires in 

 svti<>n (liir. -09 4 ) an oval form, and pre- 

 Benta a dilli-rent condition in its dor>al 

 (sd) and ventral (od) halves, the latter 

 being at the same time in immediate con- 

 tact with the jK'iiton -al epit helium. The 

 nie>one]>hric tubules open into thedoi>al 

 hair', while vc-ntrally the wall is consider- 

 ably thickened. Tlien a >eparation of the 

 two pails takes place, which begins at a 

 little di>t;,nce from the anterior , nd 

 sections 3-1) and proceeds back \\ai-d to 

 tlie point of opening into the hind gut. 

 Of the parts which ivsult iVoi-i tin- !i>-i>n. 

 that which lies dtwsally ' s the permanent 

 mesonephrio dud (/''/); it exhibits at th-M 



a broad lumen and receiv. s the urinary 

 tubuhs (tig. *2u7 .s7>. \' en t rally, between it and the epithelium of 

 the body-cavity, lio the Miill.-rian duct dig. L'nl) od and iig. \ 

 which is at first only a narrow passage, but later a much enlarged 

 one. In the process of lission the anterior initial part of the primary 

 canal (fig. 207 pd), which was described at p. '>'>'< a- pron.-phros liUl { 

 which opens into the body-cavity by means of a ciliate funnel (o), 

 becomes a part of the latter duct, and the ciliate funnel becomes the 

 ostiuin abdominale tubae. 



Also in the case of the Amphibia the Mulleriuu duct is developed by being 

 split off (FCRBRINGER, Hon M ANN i t mm the mesonephric duct, with the excep- 



24 



Fig. 209. Four cros sections 

 through the anterior region 

 of the mesonephric duct of a 

 female embryo of Scylliun 

 canicula, after l>\ 



The figure shon-H how tl 



l.Tian iluet (ot?) is split off 

 from tin- iiieauiH'iilme duct 

 (sd an-: 



